The message from Windows Logs\Application for Error 22 is: Volume Shadow Copy Service error: A critical component required by the Volume Shadow Copy service is not registered. This might happened if an error occurred during Windows setup or during installation of a Shadow Copy provider. The error returned from CoCreateInstance on class with CLSID {4e14fba2-2e22-11d1-9964-00c04fbbb345} and Name CEventSystem is [0x80040154, Class not registered].

Please open the registry editor with regedit.
Expand and local to the subtree, check if there is an entry that has a ".bak" value appended. If so, this may be cause the failure when trying to resolve the SID of the writer.

Please backup the registry key first, and then delete that entry with the extra ".bak"

Then you may reboot the problematic server to check if it the issue can be fixed.

thanks for the reply. Checked all the subtrees. All were clear of any .bak entries.
Investigation seems to point to a COM+ component not properly registered or corrupt (COM+ Applications). Checking that.